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Reversible electrowetting on superhydrophobic silicon nanowires
Nicolas Verplanck1, Elisabeth Galopin, Jean-Christophe Camart
1Institut d'Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS-8520, Cité Scientifique, Avenue Poincaré, BP. 60069, 59652 Villeneuve d'Ascq, France.
Nano Letters
|February 17, 2007
Summary
This study demonstrates reversible electrowetting on superhydrophobic silicon nanowires (SiNWs). These surfaces allow controlled manipulation of liquid droplets using an applied voltage, crucial for microfluidic applications.
Area of Science:
- Materials Science
- Surface Science
- Nanotechnology
Background:
- Superhydrophobic surfaces exhibit high contact angles and low hysteresis, enabling droplet manipulation.
- Electrowetting offers a method to dynamically alter surface wettability using electric fields.
- Controlling liquid behavior on nanostructured surfaces is vital for advanced applications.
Purpose of the Study:
- To investigate the electrowetting behavior of liquid droplets on superhydrophobic silicon nanowires (SiNWs).
- To demonstrate reversible control over droplet contact angles in different environments.
- To explore the potential of SiNWs for tunable liquid handling.
Main Methods:
- Silicon nanowires (SiNWs) were fabricated on Si/SiO2 substrates via the vapor-liquid-solid (VLS) mechanism.
- The SiNW surfaces were electrically insulated with a 300 nm SiO2 layer and hydrophobized with a fluoropolymer (C4F8).
- Electrowetting experiments were conducted using a saline solution (100 mM KCl) in air and oil, with applied voltages up to 150 VTRMS.
Main Results:
- The superhydrophobic SiNW surfaces achieved a liquid contact angle (Theta) of approximately 160 degrees in air with minimal hysteresis.
- Electrowetting reversibly decreased the contact angle by up to 23 degrees at 150 VTRMS in air.
- The electrowetting effect was observed in both air and oil environments.
Conclusions:
- Superhydrophobic silicon nanowires are effective platforms for reversible electrowetting.
- The ability to tune droplet contact angles on SiNWs opens possibilities for microfluidic devices.
- This research advances the control of liquid behavior on nanostructured materials.
